Binocular-type stereoscopic televisions and movies using eyeglasses have become popular in recent years. Multi-eye type stereoscopic displays without a need of eyeglasses have also been developed. A technique of displaying a 3D image of binocular type or of multi-eye type uses, however, only part of factors which enables stereoscopy (such as binocular parallax, convergence, focusing, and motion parallax). Without effect of the focusing, in particular, such problems may occur that viewers of a stereoscopic image displayed with the above-described techniques feel fatigued, have headache, or the like.
In the meantime, a 3D image displayed using a technique of electronic holography satisfies all of the above-described factors for stereoscopy, and is thus considered to be capable of providing a 3D image which is naturally acceptable and has less burden on a human body. The electronic holography displays a 3D reconstructed image in such a manner that: data on a hologram is acquired with a method of directly photographing a hologram using an electrical imaging element such as a CCD (Charge Coupled Device) or with a CGH (Computer Generated Hologram) which computes a hologram based on 3D spatial information of an object; and a spatial light modulator (SLM) such as a liquid crystal panel displays the hologram.